The present invention relates to a lever operated rotary drive mechanism, in particular, but not exclusively a rotary drive mechanism for a seat reclining mechanism.
Reclinable vehicle seats are known which have a seat cushion pivotally connected to a seat back and a seat reclining mechanism which controls the inclination of the seat back relative to the seat cushion.
One known type of seat reclining mechanism, for example as disclosed in UK patent 1586869, is permanently engaged and provides continuous angular adjustment between the seat back and seat cushion. This type of seat reclining mechanism usually includes planetary gear assembly driven by a drive shaft. Rotation of the drive shaft in one direction causes angular displacement of the seat back in one direction (ie. backwards direction of the seat) and rotation of the drive shaft in the opposite direction causes angular displacement of the seat back in the opposite direction (ie. forwards direction of the seat).
An advantage of the continuously adjustable type of seat reclining mechanism is that the seat back is positively driven in both the forward and rearward directions.
A further advantage is that, due to the permanent engagement of the drive mechanism, the seat back and seat cushion are always mechanically locked together during adjustment thereby rendering the adjustment process safe.
Manual rotation of the drive shaft of the continuously adjustable type of seat reclining mechanism is conventionally achieved by mounting a handle on the drive shaft. Accordingly, the handle is located on one side of the seat immediately adjacent to the pivotal connection between the seat cushion and seat back.
Unfortunately access to the handle may be restricted in certain designs of vehicle (due to the position of structural components of the vehicle body and/or trim) or seats, eg. seats having arm rests.
In addition, the operative needs to twist the handle in order to apply torque to the drive shaft for operating the mechanism. This operation can be rendered more difficult when there is restricted access.
According to one aspect of the present invention there is provided a lever operated rotary drive mechanism, the mechanism including a mounting frame carrying a rotary output member adapted for driving engagement with a rotary drive input, such as a shaft, an operating lever pivotally mounted on the mounting frame for pivotal angular displacement relative to the frame, biasing means for biasing the lever to a rest angular position, the lever being movable within a first angular displacement region located on one side of said rest position and movable within a second angular displacement region located on the opposite side of said rest position and a drive transmission which drivingly connects the lever to the output member to cause rotation of the output member in one rotary direction only on displacement of the lever within said first angular displacement region and to cause rotation of the output member in the opposite rotary direction only on displacement of the lever within said second angular displacement region.
According to another aspect of the present invention there is provided a reclinable seat having a seat cushion pivotally connected to a seat back, a continually adjustable seat reclining mechanism having a rotary input for causing operation of the seat reclining mechanism and a lever operated rotary drive mechanism as defined above drivingly connected to said rotary input.